1. Technical Field
The present invention relates to data storage libraries in general, and in particular to a data storage library having a robotic assembly operating on a guide rail. Still more particularly, the present invention relates to a tape library storage system having a robotic assembly operating on a guide rail with linear and curved sections.
2. Description of Related Art
An automated data storage library typically uses a mechanical robot to pick and place data storage cartridges into media drives and empty cartridge slots. The mechanical robot is often a self-supporting mechanism having a picker assembly at the end of an arm that can be moved in two or more directions. The robotic movement is commonly controlled by some type of actuator, and the number of actuators is often equal to, but not limited by the number of directions the mechanical robot moves. By using the electronic encoders on the actuators, the picker assembly can be positioned in proximity to the media drives or cartridge slots.
Some attempts have been made to alleviate the constraints of stand alone robotic arms by implementing carousel structures, draw cable devices, and track/rail type systems. These systems have some sort of guide rail (or track) and a carriage that moves the storage media cartridges to and from the media drives. The guide rail forms a path for directing the carriage to any desired position, be it in a continuous loop of a carousel, a straight line, or other combinations of straight and curved sections.
Guide rail and carriage system configurations generally use a rack and pinion arrangement that includes a pair of gears capable of converting rotational motion into linear motion. Typically, a circular pinion engages a linear rack located on a flat bar. Rotational motion applied to the circular pinion will cause the linear rack to move sideways up to the limit of its travel.
A guide rail and carriage guidance mechanism is desired to include both straight and curved sections in the guide rail. In order for a pinion to travel on a curved rack with the axis of the pinion perpendicular to the axis of curvature of the curved rack (when going around a curved section), the teeth on the curved rack must be aligned with the teeth of the pinion during rotation. As such, an intricate combination of pinion teeth/rack teeth must be designed in order to accomplish such purpose. For example, the rack teeth must be tapered in order to fit the curvature of the curved rack. Similarly, the mating pinion teeth must also be tapered in order to match the rack teeth such that proper meshing of the pinion teeth and the rack teeth can be achieved as the pinion travels on the curved rack. However, it is not possible for such pinion to continue on in a linear rack after the curve rack because regular straight pinion teeth are required.
The present disclosure provides an automated data storage library having an improved robotic assembly operating on a guide rail with linear and curved sections.